- Enterasys Security Router User's Guide

Features
4-4 Configuring T1/E1 & T3/E3 Interfaces
• Clear Channel service is similar to the full rate service except that the data stream rate is slightly
higher because the framing overhead bits are also used to deliver data.
– T3 - Not Available
– E3 - 34.368Mbps payload
T1 Drop & Insert One-to-One DS0 Bypassing
The XSR’s 2-port D&I NIM is designed to cross-connect unused timeslots between the two ports
and provide one T1/E1 line for both data and voice traffic, as shown in Figure 4-1. The timeslots
carrying data are terminated in the on-board HDLC controller, while voice timeslots bypass the
D&I NIM and are terminated in the downstream PBX. This NIM is configured with
drop-and-
insert-group
and runs identically to the XSR’s 2-port fractional T1/E1 NIM. Show controller
t1 s/c/x
is useful for debugging the line. Refer to the XSR CLI Reference Guide for associated
commands.
Figure 4-1 Drop and Insert NIM Topology
The D&I NIM does not support channelized mode nor PRI.
Drop and Insert Features
The following features are supported by the D&I NIM:
• The D&I feature allows Channel Associated Signaling (CAS) voice DS0 timeslots to be taken
off the Central Office (CO) T1 or E1 interface and inserted into timeslots of the PBX T1 or E1
interface, as long as both interfaces are on the same NIM card.
•You must configure the timeslots belonging to the data channel group. All timeslots not within
the data channel group are considered idle and bypassed between the T1 or E1 ports.
• D&I timeslots need not be contiguous - all idle timeslots on both the T1 or E1 interface will be
automatically connected and transparently pass voice channels. Idle timeslots are not
configured to take part in channel groups.
• The CO T1/E1 and PBX T1/E1 ports are bypassed by relays to maintain a CO-PBX link in case
of a power outage or watchdog timeout. So, when the XSR with the D&I NIM is inserted
between the PBX and the T1 line of the CO, there is no need to reconfigure the PBX.
Note: If the XSR loses power, the two T1 lines will be cross-connected by the relays. Consequently,
the Central Office will not report the lines down.
PSTN
Frame
Relay
PBX
T1-PBX
Clock
T1-CO
Voice timeslots
bypass the XSR
Data timeslots
terminate in the XSR
Clock